/*
 ** $Id: loadlib.c,v 1.52.1.3 2008/08/06 13:29:28 roberto Exp $
 ** Dynamic library loader for Lua
 ** See Copyright Notice in lua.h
 **
 ** This module contains an implementation of loadlib for Unix systems
 ** that have dlfcn, an implementation for Darwin (Mac OS X), an
 ** implementation for Windows, and a stub for other systems.
 */

using System;
using System.IO;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
using System.Diagnostics;

namespace KopiLua
{
    public partial class Lua
    {

        /* prefix for open functions in C libraries */
        public const string LUA_POF = "luaopen_";

        /* separator for open functions in C libraries */
        public const string LUA_OFSEP = "_";


        public const string LIBPREFIX = "LOADLIB: ";

        public const string POF = LUA_POF;
        public const string LIB_FAIL = "open";


        /* error codes for ll_loadfunc */
        public const int ERRLIB			= 1;
        public const int ERRFUNC		= 2;

        //public static void setprogdir(lua_State L) { }

        public static void setprogdir(lua_State L)
        {
            CharPtr buff = Directory.GetCurrentDirectory();
            luaL_gsub(L, lua_tostring(L, -1), LUA_EXECDIR, buff);
            lua_remove(L, -2);  /* remove original string */
        }


        #if LUA_DL_DLOPEN
        /*
         ** {========================================================================
         ** This is an implementation of loadlib based on the dlfcn interface.
         ** The dlfcn interface is available in Linux, SunOS, Solaris, IRIX, FreeBSD,
         ** NetBSD, AIX 4.2, HPUX 11, and  probably most other Unix flavors, at least
         ** as an emulation layer on top of native functions.
         ** =========================================================================
         */

        //#include <dlfcn.h>

        static void ll_unloadlib (void *lib) {
            dlclose(lib);
        }


        static void *ll_load (lua_State L, readonly CharPtr path) {
            void *lib = dlopen(path, RTLD_NOW);
            if (lib == null) lua_pushstring(L, dlerror());
            return lib;
        }


        static lua_CFunction ll_sym (lua_State L, void *lib, readonly CharPtr sym) {
            lua_CFunction f = (lua_CFunction)dlsym(lib, sym);
            if (f == null) lua_pushstring(L, dlerror());
            return f;
        }

        /* }====================================================== */



        //#elif defined(LUA_DL_DLL)
        /*
         ** {======================================================================
         ** This is an implementation of loadlib for Windows using native functions.
         ** =======================================================================
         */

        //#include <windows.h>


        //#undef setprogdir

        static void setprogdir (lua_State L) {
            char buff[MAX_PATH + 1];
            char *lb;
            DWORD nsize = sizeof(buff)/GetUnmanagedSize(typeof(char));
            DWORD n = GetModuleFileNameA(null, buff, nsize);
            if (n == 0 || n == nsize || (lb = strrchr(buff, '\\')) == null)
                luaL_error(L, "unable to get ModuleFileName");
            else {
                *lb = '\0';
                luaL_gsub(L, lua_tostring(L, -1), LUA_EXECDIR, buff);
                lua_remove(L, -2);  /* remove original string */
            }
        }


        static void pusherror (lua_State L) {
            int error = GetLastError();
            char buffer[128];
            if (FormatMessageA(FORMAT_MESSAGE_IGNORE_INSERTS | FORMAT_MESSAGE_FROM_SYSTEM,
                               null, error, 0, buffer, sizeof(buffer), null))
                lua_pushstring(L, buffer);
            else
                lua_pushfstring(L, "system error %d\n", error);
        }

        static void ll_unloadlib (void *lib) {
            FreeLibrary((HINSTANCE)lib);
        }


        static void *ll_load (lua_State L, readonly CharPtr path) {
            HINSTANCE lib = LoadLibraryA(path);
            if (lib == null) pusherror(L);
            return lib;
        }


        static lua_CFunction ll_sym (lua_State L, void *lib, readonly CharPtr sym) {
            lua_CFunction f = (lua_CFunction)GetProcAddress((HINSTANCE)lib, sym);
            if (f == null) pusherror(L);
            return f;
        }

        /* }====================================================== */



        #elif LUA_DL_DYLD
        /*
         ** {======================================================================
         ** Native Mac OS X / Darwin Implementation
         ** =======================================================================
         */

        //#include <mach-o/dyld.h>


        /* Mac appends a `_' before C function names */
        //#undef POF
        //#define POF	"_" LUA_POF


        static void pusherror (lua_State L) {
            CharPtr err_str;
            CharPtr err_file;
            NSLinkEditErrors err;
            int err_num;
            NSLinkEditError(err, err_num, err_file, err_str);
            lua_pushstring(L, err_str);
        }


        static CharPtr errorfromcode (NSObjectFileImageReturnCode ret) {
            switch (ret) {
                case NSObjectFileImageInappropriateFile:
                    return "file is not a bundle";
                case NSObjectFileImageArch:
                    return "library is for wrong CPU type";
                case NSObjectFileImageFormat:
                    return "bad format";
                case NSObjectFileImageAccess:
                    return "cannot access file";
                case NSObjectFileImageFailure:
                default:
                    return "unable to load library";
            }
        }


        static void ll_unloadlib (void *lib) {
            NSUnLinkModule((NSModule)lib, NSUNLINKMODULE_OPTION_RESET_LAZY_REFERENCES);
        }


        static void *ll_load (lua_State L, readonly CharPtr path) {
            NSObjectFileImage img;
            NSObjectFileImageReturnCode ret;
            /* this would be a rare case, but prevents crashing if it happens */
            if(!_dyld_present()) {
                lua_pushliteral(L, "dyld not present");
                return null;
            }
            ret = NSCreateObjectFileImageFromFile(path, img);
            if (ret == NSObjectFileImageSuccess) {
                NSModule mod = NSLinkModule(img, path, NSLINKMODULE_OPTION_PRIVATE |
                                            NSLINKMODULE_OPTION_RETURN_ON_ERROR);
                NSDestroyObjectFileImage(img);
                if (mod == null) pusherror(L);
                return mod;
            }
            lua_pushstring(L, errorfromcode(ret));
            return null;
        }


        static lua_CFunction ll_sym (lua_State L, void *lib, readonly CharPtr sym) {
            NSSymbol nss = NSLookupSymbolInModule((NSModule)lib, sym);
            if (nss == null) {
                lua_pushfstring(L, "symbol " + LUA_QS + " not found", sym);
                return null;
            }
            return (lua_CFunction)NSAddressOfSymbol(nss);
        }

        /* }====================================================== */



        #else
        /*
         ** {======================================================
         ** Fallback for other systems
         ** =======================================================
         */

        //#undef LIB_FAIL
        //#define LIB_FAIL	"absent"


        public const string DLMSG = "dynamic libraries not enabled; check your Lua installation";


        public static void ll_unloadlib (object lib) {
            //(void)lib;  /* to avoid warnings */
        }


        public static object ll_load (lua_State L, CharPtr path) {
            //(void)path;  /* to avoid warnings */
            lua_pushliteral(L, DLMSG);
            return null;
        }


        public static lua_CFunction ll_sym (lua_State L, object lib, CharPtr sym) {
            //(void)lib; (void)sym;  /* to avoid warnings */
            lua_pushliteral(L, DLMSG);
            return null;
        }

        /* }====================================================== */
        #endif



        private static object ll_register (lua_State L, CharPtr path) {
            // todo: the whole usage of plib here is wrong, fix it - mjf
            //void **plib;
            object plib = null;
            lua_pushfstring(L, "%s%s", LIBPREFIX, path);
            lua_gettable(L, LUA_REGISTRYINDEX);  /* check library in registry? */
            if (!lua_isnil(L, -1))  /* is there an entry? */
            plib = lua_touserdata(L, -1);
            else {  /* no entry yet; create one */
                lua_pop(L, 1);
                //plib = lua_newuserdata(L, (uint)Marshal.SizeOf(plib));
                //plib[0] = null;
                luaL_getmetatable(L, "_LOADLIB");
                lua_setmetatable(L, -2);
                lua_pushfstring(L, "%s%s", LIBPREFIX, path);
                lua_pushvalue(L, -2);
                lua_settable(L, LUA_REGISTRYINDEX);
            }
            return plib;
        }


        /*
         ** __gc tag method: calls library's `ll_unloadlib' function with the lib
         ** handle
         */
        private static int gctm (lua_State L) {
            object lib = luaL_checkudata(L, 1, "_LOADLIB");
            if (lib != null) ll_unloadlib(lib);
            lib = null;  /* mark library as closed */
            return 0;
        }


        private static int ll_loadfunc (lua_State L, CharPtr path, CharPtr sym) {
            object reg = ll_register(L, path);
            if (reg == null) reg = ll_load(L, path);
            if (reg == null)
                return ERRLIB;  /* unable to load library */
            else {
                lua_CFunction f = ll_sym(L, reg, sym);
                if (f == null)
                    return ERRFUNC;  /* unable to find function */
                lua_pushcfunction(L, f);
                return 0;  /* return function */
            }
        }


        private static int ll_loadlib (lua_State L) {
            CharPtr path = luaL_checkstring(L, 1);
            CharPtr init = luaL_checkstring(L, 2);
            int stat = ll_loadfunc(L, path, init);
            if (stat == 0)  /* no errors? */
            return 1;  /* return the loaded function */
            else {  /* error; error message is on stack top */
                lua_pushnil(L);
                lua_insert(L, -2);
                lua_pushstring(L, (stat == ERRLIB) ?  LIB_FAIL : "init");
                return 3;  /* return nil, error message, and where */
            }
        }



        /*
         ** {======================================================
         ** 'require' function
         ** =======================================================
         */


        private static int readable (CharPtr filename) {
            Stream f = fopen(filename, "r");  /* try to open file */
            if (f == null) return 0;  /* open failed */
            fclose(f);
            return 1;
        }


        private static CharPtr pushnexttemplate (lua_State L, CharPtr path) {
            CharPtr l;
            while (path[0] == LUA_PATHSEP[0]) path = path.next();  /* skip separators */
            if (path[0] == '\0') return null;  /* no more templates */
            l = strchr(path, LUA_PATHSEP[0]);  /* find next separator */
            if (l == null) l = path + strlen(path);
            lua_pushlstring(L, path, (uint)(l - path));  /* template */
            return l;
        }


        private static CharPtr findfile (lua_State L, CharPtr name,
                                         CharPtr pname) {
            CharPtr path;
            name = luaL_gsub(L, name, ".", LUA_DIRSEP);
            lua_getfield(L, LUA_ENVIRONINDEX, pname);
            path = lua_tostring(L, -1);
            if (path == null)
                luaL_error(L, LUA_QL("package.%s") + " must be a string", pname);
            lua_pushliteral(L, "");  /* error accumulator */
            while ((path = pushnexttemplate(L, path)) != null) {
                CharPtr filename;
                filename = luaL_gsub(L, lua_tostring(L, -1), LUA_PATH_MARK, name);
                lua_remove(L, -2);  /* remove path template */
                if (readable(filename) != 0)  /* does file exist and is readable? */
                return filename;  /* return that file name */
                lua_pushfstring(L, "\n\tno file " + LUA_QS, filename);
                lua_remove(L, -2);  /* remove file name */
                lua_concat(L, 2);  /* add entry to possible error message */
            }
            return null;  /* not found */
        }


        private static void loaderror (lua_State L, CharPtr filename) {
            luaL_error(L, "error loading module " + LUA_QS + " from file " + LUA_QS + ":\n\t%s",
                       lua_tostring(L, 1), filename, lua_tostring(L, -1));
        }


        private static int loader_Lua (lua_State L) {
            CharPtr filename;
            CharPtr name = luaL_checkstring(L, 1);
            filename = findfile(L, name, "path");
            if (filename == null) return 1;  /* library not found in this path */
            if (luaL_loadfile(L, filename) != 0)
                loaderror(L, filename);
            return 1;  /* library loaded successfully */
        }


        private static CharPtr mkfuncname (lua_State L, CharPtr modname) {
            CharPtr funcname;
            CharPtr mark = strchr(modname, LUA_IGMARK[0]);
            if (mark!=null) modname = mark + 1;
            funcname = luaL_gsub(L, modname, ".", LUA_OFSEP);
            funcname = lua_pushfstring(L, POF + "%s", funcname);
            lua_remove(L, -2);  /* remove 'gsub' result */
            return funcname;
        }


        private static int loader_C (lua_State L) {
            CharPtr funcname;
            CharPtr name = luaL_checkstring(L, 1);
            CharPtr filename = findfile(L, name, "cpath");
            if (filename == null) return 1;  /* library not found in this path */
            funcname = mkfuncname(L, name);
            if (ll_loadfunc(L, filename, funcname) != 0)
                loaderror(L, filename);
            return 1;  /* library loaded successfully */
        }


        private static int loader_Croot (lua_State L) {
            CharPtr funcname;
            CharPtr filename;
            CharPtr name = luaL_checkstring(L, 1);
            CharPtr p = strchr(name, '.');
            int stat;
            if (p == null) return 0;  /* is root */
            lua_pushlstring(L, name, (uint)(p - name));
            filename = findfile(L, lua_tostring(L, -1), "cpath");
            if (filename == null) return 1;  /* root not found */
            funcname = mkfuncname(L, name);
            if ((stat = ll_loadfunc(L, filename, funcname)) != 0) {
                if (stat != ERRFUNC) loaderror(L, filename);  /* real error */
                lua_pushfstring(L, "\n\tno module " + LUA_QS + " in file " + LUA_QS,
                                name, filename);
                return 1;  /* function not found */
            }
            return 1;
        }


        private static int loader_preload (lua_State L) {
            CharPtr name = luaL_checkstring(L, 1);
            lua_getfield(L, LUA_ENVIRONINDEX, "preload");
            if (!lua_istable(L, -1))
                luaL_error(L, LUA_QL("package.preload") + " must be a table");
            lua_getfield(L, -1, name);
            if (lua_isnil(L, -1))  /* not found? */
            lua_pushfstring(L, "\n\tno field package.preload['%s']", name);
            return 1;
        }


        public static object sentinel = new object();


        public static int ll_require (lua_State L) {
            CharPtr name = luaL_checkstring(L, 1);
            int i;
            lua_settop(L, 1);  /* _LOADED table will be at index 2 */
            lua_getfield(L, LUA_REGISTRYINDEX, "_LOADED");
            lua_getfield(L, 2, name);
            if (lua_toboolean(L, -1) != 0) {  /* is it there? */
                if (lua_touserdata(L, -1) == sentinel)  /* check loops */
                luaL_error(L, "loop or previous error loading module " + LUA_QS, name);
                return 1;  /* package is already loaded */
            }
            /* else must load it; iterate over available loaders */
            lua_getfield(L, LUA_ENVIRONINDEX, "loaders");
            if (!lua_istable(L, -1))
                luaL_error(L, LUA_QL("package.loaders") + " must be a table");
            lua_pushliteral(L, "");  /* error message accumulator */
            for (i=1; ; i++) {
                lua_rawgeti(L, -2, i);  /* get a loader */
                if (lua_isnil(L, -1))
                    luaL_error(L, "module " + LUA_QS + " not found:%s",
                               name, lua_tostring(L, -2));
                lua_pushstring(L, name);
                lua_call(L, 1, 1);  /* call it */
                if (lua_isfunction(L, -1))  /* did it find module? */
                break;  /* module loaded successfully */
                else if (lua_isstring(L, -1) != 0)  /* loader returned error message? */
                lua_concat(L, 2);  /* accumulate it */
                else
                    lua_pop(L, 1);
            }
            lua_pushlightuserdata(L, sentinel);
            lua_setfield(L, 2, name);  /* _LOADED[name] = sentinel */
            lua_pushstring(L, name);  /* pass name as argument to module */
            lua_call(L, 1, 1);  /* run loaded module */
            if (!lua_isnil(L, -1))  /* non-nil return? */
            lua_setfield(L, 2, name);  /* _LOADED[name] = returned value */
            lua_getfield(L, 2, name);
            if (lua_touserdata(L, -1) == sentinel) {   /* module did not set a value? */
                lua_pushboolean(L, 1);  /* use true as result */
                lua_pushvalue(L, -1);  /* extra copy to be returned */
                lua_setfield(L, 2, name);  /* _LOADED[name] = true */
            }
            return 1;
        }

        /* }====================================================== */



        /*
         ** {======================================================
         ** 'module' function
         ** =======================================================
         */
        

        private static void setfenv (lua_State L) {
            lua_Debug ar = new lua_Debug();
            if (lua_getstack(L, 1, ar) == 0 ||
                lua_getinfo(L, "f", ar) == 0 ||  /* get calling function */
                lua_iscfunction(L, -1))
                luaL_error(L, LUA_QL("module") + " not called from a Lua function");
            lua_pushvalue(L, -2);
            lua_setfenv(L, -2);
            lua_pop(L, 1);
        }


        private static void dooptions (lua_State L, int n) {
            int i;
            for (i = 2; i <= n; i++) {
                lua_pushvalue(L, i);  /* get option (a function) */
                lua_pushvalue(L, -2);  /* module */
                lua_call(L, 1, 0);
            }
        }


        private static void modinit (lua_State L, CharPtr modname) {
            CharPtr dot;
            lua_pushvalue(L, -1);
            lua_setfield(L, -2, "_M");  /* module._M = module */
            lua_pushstring(L, modname);
            lua_setfield(L, -2, "_NAME");
            dot = strrchr(modname, '.');  /* look for last dot in module name */
            if (dot == null) dot = modname;
            else dot = dot.next();
            /* set _PACKAGE as package name (full module name minus last part) */
            lua_pushlstring(L, modname, (uint)(dot - modname));
            lua_setfield(L, -2, "_PACKAGE");
        }


        private static int ll_module (lua_State L) {
            CharPtr modname = luaL_checkstring(L, 1);
            int loaded = lua_gettop(L) + 1;  /* index of _LOADED table */
            lua_getfield(L, LUA_REGISTRYINDEX, "_LOADED");
            lua_getfield(L, loaded, modname);  /* get _LOADED[modname] */
            if (!lua_istable(L, -1)) {  /* not found? */
                lua_pop(L, 1);  /* remove previous result */
                /* try global variable (and create one if it does not exist) */
                if (luaL_findtable(L, LUA_GLOBALSINDEX, modname, 1) != null)
                    return luaL_error(L, "name conflict for module " + LUA_QS, modname);
                lua_pushvalue(L, -1);
                lua_setfield(L, loaded, modname);  /* _LOADED[modname] = new table */
            }
            /* check whether table already has a _NAME field */
            lua_getfield(L, -1, "_NAME");
            if (!lua_isnil(L, -1))  /* is table an initialized module? */
            lua_pop(L, 1);
            else {  /* no; initialize it */
                lua_pop(L, 1);
                modinit(L, modname);
            }
            lua_pushvalue(L, -1);
            setfenv(L);
            dooptions(L, loaded - 1);
            return 0;
        }


        private static int ll_seeall (lua_State L) {
            luaL_checktype(L, 1, LUA_TTABLE);
            if (lua_getmetatable(L, 1)==0) {
                lua_createtable(L, 0, 1); /* create new metatable */
                lua_pushvalue(L, -1);
                lua_setmetatable(L, 1);
            }
            lua_pushvalue(L, LUA_GLOBALSINDEX);
            lua_setfield(L, -2, "__index");  /* mt.__index = _G */
            return 0;
        }


        /* }====================================================== */



        /* auxiliary mark (for internal use) */
        public readonly static string AUXMARK		= String.Format("{0}", (char)1);

        private static void setpath (lua_State L, CharPtr fieldname, CharPtr envname,
                                     CharPtr def) {
            CharPtr path = getenv(envname);
            if (path == null)  /* no environment variable? */
            lua_pushstring(L, def);  /* use default */
            else {
                /* replace ";;" by ";AUXMARK;" and then AUXMARK by default path */
                path = luaL_gsub(L, path, LUA_PATHSEP + LUA_PATHSEP,
                                 LUA_PATHSEP + AUXMARK + LUA_PATHSEP);
                luaL_gsub(L, path, AUXMARK, def);
                lua_remove(L, -2);
            }
            setprogdir(L);
            lua_setfield(L, -2, fieldname);
        }


        private readonly static luaL_Reg[] pk_funcs = {
            new luaL_Reg("loadlib", ll_loadlib),
            new luaL_Reg("seeall", ll_seeall),
            new luaL_Reg(null, null)
        };


        private readonly static luaL_Reg[] ll_funcs = {
            new luaL_Reg("module", ll_module),
            new luaL_Reg("require", ll_require),
            new luaL_Reg(null, null)
        };


        public readonly static lua_CFunction[] loaders =
        {loader_preload, loader_Lua, loader_C, loader_Croot, null};


        public static int luaopen_package (lua_State L) {
            int i;
            /* create new type _LOADLIB */
            luaL_newmetatable(L, "_LOADLIB");
            lua_pushcfunction(L, gctm);
            lua_setfield(L, -2, "__gc");
            /* create `package' table */
            luaL_register(L, LUA_LOADLIBNAME, pk_funcs);
            #if LUA_COMPAT_LOADLIB
            lua_getfield(L, -1, "loadlib");
            lua_setfield(L, LUA_GLOBALSINDEX, "loadlib");
            #endif
            lua_pushvalue(L, -1);
            lua_replace(L, LUA_ENVIRONINDEX);
            /* create `loaders' table */
            //lua_createtable(L, 0, loaders.Length - 1);
            lua_createtable(L, loaders.Length - 1, 0);
            //lua_createtable(L, sizeof(loaders) / sizeof(loaders[0]) - 1, 0);
            /* fill it with pre-defined loaders */
            for (i=0; loaders[i] != null; i++) {
                lua_pushcfunction(L, loaders[i]);
                lua_rawseti(L, -2, i+1);
            }
            lua_setfield(L, -2, "loaders");  /* put it in field `loaders' */
            setpath(L, "path", LUA_PATH, LUA_PATH_DEFAULT);  /* set field `path' */
            setpath(L, "cpath", LUA_CPATH, LUA_CPATH_DEFAULT); /* set field `cpath' */
            /* store config information */
            lua_pushliteral(L, LUA_DIRSEP + "\n" + LUA_PATHSEP + "\n" + LUA_PATH_MARK + "\n" +
                            LUA_EXECDIR + "\n" + LUA_IGMARK);
            lua_setfield(L, -2, "config");
            /* set field `loaded' */
            luaL_findtable(L, LUA_REGISTRYINDEX, "_LOADED", 2);
            lua_setfield(L, -2, "loaded");
            /* set field `preload' */
            lua_newtable(L);
            lua_setfield(L, -2, "preload");
            lua_pushvalue(L, LUA_GLOBALSINDEX);
            luaL_register(L, null, ll_funcs);  /* open lib into global table */
            lua_pop(L, 1);
            return 1;  /* return 'package' table */
        }

    }
}
